{"raw_statement":[{"iden":"problem statement","content":"Snuke has an integer sequence $A$ of length $N$.\nHe will freely choose an integer $b$. Here, he will get sad if $A_i$ and $b+i$ are far from each other. More specifically, the _sadness_ of Snuke is calculated as follows:\n\n*   $abs(A_1 - (b+1)) + abs(A_2 - (b+2)) + ... + abs(A_N - (b+N))$\n\nHere, $abs(x)$ is a function that returns the absolute value of $x$.\nFind the minimum possible sadness of Snuke."},{"iden":"constraints","content":"*   $1 \\leq N \\leq 2 \\times 10^5$\n*   $1 \\leq A_i \\leq 10^9$\n*   All values in input are integers."},{"iden":"input","content":"Input is given from Standard Input in the following format:\n\n$N$\n$A_1$ $A_2$ $...$ $A_N$"},{"iden":"sample input 1","content":"5\n2 2 3 5 5"},{"iden":"sample output 1","content":"2\n\nIf we choose $b=0$, the sadness of Snuke would be $abs(2-(0+1))+abs(2-(0+2))+abs(3-(0+3))+abs(5-(0+4))+abs(5-(0+5))=2$. Any choice of $b$ does not make the sadness of Snuke less than $2$, so the answer is $2$."},{"iden":"sample input 2","content":"9\n1 2 3 4 5 6 7 8 9"},{"iden":"sample output 2","content":"0"},{"iden":"sample input 3","content":"6\n6 5 4 3 2 1"},{"iden":"sample output 3","content":"18"},{"iden":"sample input 4","content":"7\n1 1 1 1 2 3 4"},{"iden":"sample output 4","content":"6"}],"translated_statement":null,"sample_group":[],"show_order":["default"],"formal_statement":null,"simple_statement":null,"has_page_source":true}